WinRT application suspension clarification

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WinRT application suspension clarification

Anonymous

I recently posted this question which mainly works. The problem is my code gets run when I minimize the program and not when I Exit. Granted that minimize is more of a suspension than Exit is, but I found this and it says to follow the directions so suspension happens when I Exit.

I revisited that page and discovered I was missing the part where I handle the exit request, but since it is written in CS and I am writing mine in WinRT/C++, I am having difficulty in rewriting the code. Here is the code that has me stumped.

public MainPage()
{
     this.InitializeComponent();
     Windows.UI.Core.Preview.SystemNavigationManagerPreview.GetForCurrentView().CloseRequested +=
         async (sender, args) =>
         {
             args.Handled = true;
             var result = await SaveConfirm.ShowAsync();
             if (result == ContentDialogResult.Primary)
             {
                 // Save work;
             }
             else
             {
                 App.Current.Exit();
             }
         };
 }

So I need to put this in my MainPage.cpp. I get that CloseRequested() is just a listener for the close button. I am struggling with the next line that is an async() and the +=. (I sort of understand the meaning of this code, but WinRT has no equivalent).

The rest of the lines of code I get as I have used a ContentDialog before. I am not sure how to make this work for WinRT/C++. Thanks for your help.

Anonymous

2023-06-29T05:38:06.7866667+00:00

Haven't heard from you for a while. Any updates about this?
Anonymous

2023-07-14T15:11:56.97+00:00

Sorry about the delay. I went on vacation about a week ago and then got sick. I think I am getting over my sickness and I will post and update early next week. Thanks.

1 answer

Your answer

Anonymous

2023-06-29T05:38:06.7866667+00:00

Haven't heard from you for a while. Any updates about this?
Anonymous

2023-07-14T15:11:56.97+00:00

Sorry about the delay. I went on vacation about a week ago and then got sick. I think I am getting over my sickness and I will post and update early next week. Thanks.

Answer 1

Junjie Zhu - MSFT 21,746

Hello @Anonymous ,

Welcome to Microsoft Q&A!

You can refer to the following code.

//this is in pch.h
#include <winrt/Windows.UI.Core.Preview.h>

//this is in page header file
Windows::Foundation::IAsyncAction OnCloseRequested(Windows::Foundation::IInspectable sender, Windows::UI::Core::Preview::SystemNavigationCloseRequestedPreviewEventArgs e);

using namespace Windows::UI::Core::Preview;
using namespace Windows::UI::Xaml::Controls;

void MainPage::ClickHandler(IInspectable const&, RoutedEventArgs const&)
{
    myButton().Content(box_value(L"Clicked"));

    auto previewWnd = Windows::UI::Core::Preview::SystemNavigationManagerPreview::GetForCurrentView();
    previewWnd.CloseRequested({ this, &MainPage::OnCloseRequested });
  
}

Windows::Foundation::IAsyncAction MainPage::OnCloseRequested(IInspectable sender, SystemNavigationCloseRequestedPreviewEventArgs e)
{
    e.Handled(true);

    ContentDialog dialog;
    dialog.Title(winrt::box_value(L"Title"));
    dialog.Content(winrt::box_value(L"Content"));
    dialog.PrimaryButtonText(L"OK");

    auto result= co_await dialog.ShowAsync();

    if (result == ContentDialogResult::Primary)
    {
        // Save work;
    }
    else
    {
        Application().Current().Exit();
    }
        
}

Don't forget to add Capability confirmAppClose.

<Package ....
xmlns:rescap="http://schemas.microsoft.com/appx/manifest/foundation/windows10/restrictedcapabilities"
....IgnorableNamespaces="uap mp build rescap">

  <Capabilities>
    <Capability Name="internetClient" />
	<rescap:Capability Name="confirmAppClose" />
  </Capabilities

Thank you.

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Anonymous

2023-06-09T13:53:11.8666667+00:00
The problem is almost solved. Instead of adding my own exit button like you have shown, I adapted your code to have it trigger on pressing the exit button. So far, that all works, however, after the line that calls exit (Application().Current().Exit();) I get an exception. Here it is.

throw hresult_error(result, take_ownership_from_abi);

and the output reports this.

Exception thrown at 0x00007FFD0606CF19 (KernelBase.dll) in KCam8 GUI.exe: WinRT originate error - 0x8000FFFF : 'Catastrophic failure'.

Exception thrown at 0x00007FFD0606CF19 in KCam8 GUI.exe: Microsoft C++ exception: winrt::hresult_error at memory location 0x00000082D04FCF38.

My thought is that just abruptly exiting WinRT without allowing the code in App.cpp to run is the problem. What say you? Thanks.
Junjie Zhu - MSFT 21,746 Reputation points

2023-06-13T06:55:27.8933333+00:00

Could you please provide more code snippets? so we can reproduce your problem. Where did you put Application().Current().Exit() in App.cpp?

Anonymous

Sorry it took so long to get back to you. Here are some code snippets.

// Constructor
MainPage::MainPage(void)
{
	InitializeComponent();
	SystemNavigationManagerPreview::GetForCurrentView().CloseRequested({ this, MainPage::OnCloseRequested });

	// This is a static public property that allows downstream pages to get a handle
    // to the MainPage instance in order to call methods that are in this class.
  	MainPage::current = *this; 

	...
}

IAsyncAction MainPage::OnCloseRequested(IInspectable sender, SystemNavigationCloseRequestedPreviewEventArgs args)
{
    args.Handled(true);
    ContentDialog dialog;

	dialog.Title(winrt::box_value(L"Title"));
    dialog.Content(winrt::box_value(L"Content"));
    dialog.PrimaryButtonText(L"OK");

	auto result = co_await dialog.ShowAsync();
    if (result == ContentDialogResult::Primary)
    {
        // My code here. It causes no problems until
        // I add in the line below since I do want
        // to exit after I have saved my info. 
    }
    else
    {
        Application().Current().Exit();
    }
}

The H file.

// Exit handler prototype
IAsyncAction OnCloseRequested(IInspectable sender, SystemNavigationCloseRequestedPreviewEventArgs args); 

Paackage manifest.

<Package xmlns="http://schemas.microsoft.com/appx/manifest/foundation/windows10"
xmlns:mp="http://schemas.microsoft.com/appx/2014/phone/manifest"
xmlns:rescap="http://schemas.microsoft.com/appx/manifest/foundation/windows10/restrictedcapabilities"
IgnorableNamespaces="uap mp rescap">

<Capabilities>
	<rescap:Capability Name="confirmAppClose"/>
	<Capability Name="internetClient" />
	<Capability Name="internetClientServer"/>
	<Capability Name="privateNetworkClientServer"/>
</Capabilities>

Junjie Zhu - MSFT 21,746 Reputation points

2023-06-16T08:45:29.62+00:00

Could you please provide more code information in header file? By the way Xaml objects should not call InitializeComponent during construction, See https://github.com/microsoft/cppwinrt/tree/master/nuget#initializecomponent .

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WinRT application suspension clarification

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